Amazon made sure to mention it had "listened to our critics " when the company announced Tuesday it was raising the minimum wage for its workers to $15 an hour.

Indeed, Amazon's pay practices have faced a lot of scrutiny — Sen. Bernie Sanders has been one of the most visible and ardent critics of Amazon. Most recently, the senator introduced a bill to Congress named after CEO Jeff Bezos, and has criticized the company for its practices in terms of employee pay, benefits and safety.

But the flack Amazon has gotten hasn't come from Sanders alone. As the largest online retailer in the United States, the company has been subject to scrutiny from politicians, activist groups, and small businesses as it continues to grow.

Here's a look at the biggest criticisms leveled against Amazon in the past year:

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August 2017: Amazon's acquisition of Whole Foods further established its position as a corporation on the rise, and a target for criticisms of destroying small business while subjecting employees to poor working conditions and minimum wage.

Sarah Jacobs/Business Insider

While you may appreciate how easy it is to turn to Amazon as a one-stop retailer you don't have to leave your couch to shop at, smaller businesses are struggling to keep up with the corporation. This situation was especially evident when Amazon acquired Whole Foods, sending other grocery chains scrambling to keep up.

Amazon's dominance over the retail industry isn't anything new. Bezos' company has expanded into a variety of other industries, including healthcare, athletic apparel, and home insurance. The ability for this supercorporation to send entire retail sectors into tailspins even has its very own name — getting "Amazon'd."

Many of the concerns that have been raised over the steady rise of Amazon were once aimed at Walmart. These two mega-retailers share a history of worrisome claims over their respective working cultures. Employees of bother retailers have — for years — recounted tales of brutal working conditions, intimidating workplace regimes, and poor pay practices.

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March 2018: Sen. Bernie Sanders steps onto the scene of throwing jabs at Amazon and other corporations for their "extraordinary power." But the senator wasn't the first politician to lash out against big business — Donald Trump had already been name-dropping Amazon in several tweets for well over a year.

President Donald Trump.
Kevin Lamarque

Before Sanders zeroed in on the issue of Amazon's worker pay, the corporation had been subject to criticism from highly visible politicians.

In March, Sanders joined Trump in criticizing Amazon. The Vermont senator expressed concern about "companies like Amazon" exercising "monopoly power" in an interview with The Guardian. He followed this up by telling CNN he thought Amazon was getting "too big."

"We're seeing this incredibly large company getting involved in almost every area of commerce," Sanders told CNN. "And I think it is important to take a look at the power and influence that Amazon has."

In the same interview, Sanders does briefly mention raising the U.S. minimum wage to a "living wage" of $15 an hour, for the "millions of people who are working two or three jobs because wages are much too low."

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April 2018: Several Amazon workers told Business Insider their "horror stories" of the working conditions inside the retailer's warehouses. These accounts came soon after Bezos was named the richest man in the world.

A worker collects orders at an Amazon's fulfillment center in England.
REUTERS/Phil Noble

Workers talked about urinating in trash cans to save time and keep up with expected targets, undergoing constant surveillance while on the job, and having their breaks cut because of lines for airport-like security to get into the warehouses.

"Jeff Bezo's [sic] newly renovated home in Washington DC will have 25 bathrooms." Sanders wrote on Twitter. "Meanwhile, Amazon workers skip bathroom breaks in order to meet their grueling work targets."

Sanders also marked Prime Day by holding a town hall where employees of large corporations could talk about how they're treated at work. Sanders' comments on Prime Day marked a huge escalation in his vocal criticism of Amazon, and acted as a jumping off point for his remarks targeting the company in the months to follow.

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August 2018: Sanders steps up his attacks by highlighting the disparity between Bezos' record-setting net worth of $155 billion and the thousands of Amazon workers living on food stamps.

Sen. Bernie Sanders
Rogelio V. Solis/AP Images

Bernie Sanders started a petition in July to demand Bezos pay his employees a "living wage." This marks Sanders changing his tactics in attacking Amazon, to focus on the specific issue of worker pay.

"It is beyond absurd that you would make more money in ten seconds than the median employee of Amazon makes in an entire year," the petition reads. "I don't believe that ordinary Americans should be subsidizing the wealthiest person in the world because you pay your employees inadequate wages."

Data released in August showed that Amazon was one of the biggest corporations with workers who are relying on federal assistance. The study found that thousands of Amazon employees depended on food stamps, as well as other public programs such as Medicaid and public housing.

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August 2018: In a rare move, Amazon directly responded to Sanders. A "war of words" between Bezos and Sanders ensued over the state of Amazon's worker conditions and pay.

This very public back-and-forth between Sanders and Amazon was not the first time the two sides had interacted, however. Back in May, Amazon invited Sanders on Twitter to visit one of its fulfillment centers after another round of criticism from the senator.

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September 2018: Sanders proposed the "Stop BEZOS" bill, which would make huge companies like Amazon pay their employees better wages.

Sen. Bernie Sanders
Aaron P. Bernstein/Getty Images

The legislation (the "Stop Bad Employers by Zeroing Out Subsidies" bill) is literally named after Amazon's CEO, although Sanders did emphasize that it wasn't solely aimed at Bezos.

"I think it is fair to say that the American people are tired of having to subsidize the wealthiest people in this country who are paying wages that are just so low that people can't get by," Sanders said in a speech announcing the bill in early September.

Sanders made known he planned to introduce the bill following his back-and-forth argument with Amazon. The bill would impose a 100 percent tax on corporations that is equal to the amount of federal benefits their low-wage workers receive.

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October 2018: Amazon announced Tuesday it would be raising its minimum wage to $15 an hour, which more than doubles where it was before. Sanders and Bezos publicly exchanged praise following the announcement, and the senator quickly shifted his focus toward worker pay at other companies.

Amazon CEO Jeff Bezos.
David Ryder/Getty

Amazon's minimum wage increase will take effect November 1st, affecting more than 250,000 employees. In its announcement Tuesday that it was raising pay to $15 an hour, the corporation also expressed support for increasing the federal minimum wage from where it currently stands at $7.25.

But Amazon's acquiescence to Sanders' pressure doesn't mean the senator is done focusing on minimum wage. He encouraged other companies to follow Amazon's lead and raise their pay as well.

"There is absolutely now no reason why other profitable corporations, like Walmart, like the fast food industry, like retail in general [...] no reason now why they also should not be paying their employees at least $15 an hour," Sanders said Tuesday. "It could well be, and I think it will be, a shot heard around the world."